Visfatin is a newly discovered adipocyte hormone with a direct relationship between plasma visfatin level and type 2 diabetes mellitus. Visfatin binds to the insulin receptor at a site distinct from that of insulin and causes hypoglycaemia by reducing glucose release from liver cells and stimulating glucose utilization in adipocytes and myocytes. Visfatin is upregulated by hypoxia, inflammation and hyperglycaemia and downregulated by insulin, somatostatin and statins.
This hormone is found in the cytoplasm as well as the nucleus of cells and has been identified in many tissues and organs including the brain, kidney, lung, spleen and testis but preferentially expressed in visceral adipose tissue and upregulated in some animal models of obesity. Visceral adipose tissue is regarded to be more pernicious than subcutaneous adipose tissue. Visfatin is an endocrine,autocrine as well as paracrine peptide with many functions including enhancement of cell proliferation, biosynthesis of nicotinamide mono- and dinucleotide and hypoglycaemic effect.
Visfatin, also known as a pre-B cell colony-enhancing factor, consists of 491aa in human, chimpanzee, cattle, pig, rat and mouse, 490aa in rhesus monkey, 285aa in sheep, 587aa in opossum and 588aa in canines. Visfatin gene is well preserved during evolution. For example, the canine visfatin protein sequence is 96% and 94% identical to human and rodent visfatin, respectively. Since evidence of a direct link between visfatin genotype and human type 2 diabetes mellitus is still weak, more molecular, physiological and clinical studies are needed to determine the role of visfatin in the etiology and pathogenesis of type 2 diabetes mellitus.
Storage and Stability:Lyophilized powder may be stored at -20°C. Stable for 12 months after receipt at -20°C. Reconstitute with sterile buffer or ddH2O. Aliquot to avoid repeated freezing and thawing. Store at -20°C. Reconstituted product is stable for 6 months at -20°C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.
